9. Figure 4.2a: Epithelial tissues, p. 121. Description: Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm; the simplest of the epithelia. Function: Allows passage of materials by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae . Location: Kidney glomeruli; air sacs of lungs ; lining of heart, blood vessels, and lymphatic Vessels( ENDOTHELIUM ); lining of ventral body cavity (serosae) ( MESOTHELIUM ) Photomicrograph: Simple squamous epithelium forming part of the alveolar (air sac) walls (400x). Air sacs of lung tissue Nuclei of squamous epithelial cells (a) Simple squamous epithelium
10. Figure 4.2b: Epithelial tissues (continued), p. 121. (b) Simple cuboidal epithelium Description: Single layer of cubelike cells with large, spherical central nuclei. Function: Secretion and absorption. Location: Kidney tubules; ducts and secretory portions of small glands; ovary surface ( Germinal Epithelium). Photomicrograph: Simple cuboidal epithelium in kidney tubules (400x). Basement membrane Connective tissue Simple cuboidal epithelial cells
11. Figure 4.2c: Epithelial tissues (continued), p. 122. Description: Single layer of tall cells with round to oval nuclei; some cells bear cilia ; layer may contain mucus- secreting unicellular glands (goblet cells). Function: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action. Location: Nonciliated type lines most of the digestive tract (stomach to anal canal), gallbladder, and excretory ducts of some glands ; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus. Photomicrograph: Simple columnar epithelium of the stomach mucosa (1300x). Simple columnar epithelial cell Basement membrane (c) Simple columnar epithelium
12. Figure 4.2d: Epithelial tissues (continued), p. 122. (d) Pseudostratified columnar epithelium Description: Single layer of cells of differing heights, some not reaching the free surface ; nuclei seen at different levels but all cells touch the basement membrane ; may contain goblet cells and bear cilia. Function: Secretion, particularly of mucus; propulsion of mucus by ciliary action. Location: Nonciliated type in male’s sperm-carrying ducts and ducts of large glands; ciliated ( + mucus-secreting goblet cells) variety lines the trachea, most of the upper respiratory tract =“RESPIRATORY EPITHELIUM ” . Photomicrograph: Pseudostratified ciliated columnar epithelium lining the human trachea (400x). Trachea Cilia Pseudo- stratified epithelial layer Basement membrane Mucus of goblet cell Connective tissue
13. Figure 4.2e: Epithelial tissues (continued), pp. 123-124. Description: Thick membrane composed of several cell layers; basal cells are cuboidal or columnar and metabolically active ; surface cells are flattened (squamous) ; in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers Function: Protects underlying tissues in areas subjected to abrasion. Location : Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry membrane. Photomicrograph: Stratified squamous epithelium lining the esophagus (425x). Stratified squamous epithelium Nuclei Basement membrane Connective tissue (e) Stratified squamous epithelium
14. Stratified Columnar Epithelium Description: at least 2 layers of cells – the apical cells are columnar shaped Location: ducts of glands, pharynx and part of the male urethra Function: Secretion, Protection
15.
16. Figure 4.2f: Epithelial tissues (continued), pp. 123-124. (f) Transitional epithelium Description: Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells dome shaped or squamouslike, depending on degree of organ stretch Function: Stretches readily and permits distension of urinary organ by contained urine. Location: Lines the ureters, bladder, and part of the urethra. Photomicrograph: Transitional epithelium lining the bladder, relaxed state (500x); note the bulbous, or rounded, appearance of the cells at the surface; these cells flatten and become elongated when the bladder is filled with urine. Basement membrane Connective tissue Transitional epithelium
28. Figure 4.9a: Connective tissues, pp. 131-132. (a) Connective tissue proper: loose connective tissue, areolar Description: Gel-like matrix with all three fiber types; cells: fibroblasts, macrophages, mast cells, and some white blood cells. Function: Wraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid. Location: Widely distributed under epithelia of body, e.g., forms lamina propria of mucous membranes; packages organs; surrounds capillaries. Photomicrograph: Areolar connective tissue, a soft packaging tissue of the body (400x). Epithelium Lamina propria Fibroblast nuclei Elastic fibers Collagen fibers
29. Figure 4.9b: Connective tissues (continued), pp. 131-132. (b) Connective tissue proper: loose connective tissue, adipose Description: Matrix as in areolar, but very sparse; closely packed adipocytes, or fat cells, have nucleus pushed to the side by large fat droplet. Function: Provides reserve food fuel; insulates against heat loss; supports and protects organs. Location: Under skin; around kidneys and eyeballs; within abdomen; in breasts. Photomicrograph: Adipose tissue from the subcutaneous layer under the skin (450x). Vacuole containing fat droplet Nuclei of fat cells
30. Figure 4.9c: Connective tissues (continued), p. 133. Description: Network of reticular fibers in a typical loose ground substance; reticular cells lie on the network. Function: Fibers form a soft internal skeleton (stroma) that supports other cell types including white blood cells, mast cells, and macrophages. Location: Lymphoid organs (lymph nodes, bone marrow, and spleen). Photomicrograph: Dark-staining network of reticular connective tissue fibers forming the internal skeleton of the spleen (350 ). Spleen White blood cell (lymphocyte) Reticular fibers (c) Connective tissue proper: loose connective tissue, reticular
31. Figure 4.9d: Connective tissues (continued), p. 134. (d) Connective tissue proper: dense connective tissue, dense regular Description: Primarily parallel collagen fibers; a few elastin fibers; major cell type is the fibroblast. Function: Attaches muscles to bones or to muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one direction. Location: Tendons, most ligaments, aponeuroses. Photomicrograph: Dense regular connective tissue from a tendon (1000x). Shoulder joint Ligament Tendon Collagen fibers Nuclei of fibroblasts
32. Figure 4.9e: Connective tissues (continued), p. 134. (e) Connective tissue proper: dense connective tissue, dense irregular Description: Primarily irregularly arranged collagen fibers; some elastic fibers; major cell type is the fibroblast. Function: Able to withstand tension exerted in many directions; provides structural strength. Location: Dermis of the skin; submucosa of digestive tract; fibrous capsules of organs and of joints. Photomicrograph: Dense irregular connective tissue from the dermis of the skin (400x). Collagen fibers Nuclei of fibroblasts Fibrous joint capsule
37. Figure 4.9f: Connective tissues (continued), p. 136. Description: Amorphous but firm matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae. Function: Supports and reinforces; has resilient cushioning properties; resists compressive stress. Location: Forms most of the embryonic skeleton; covers the ends of long bones in joint cavities; forms costal cartilages of the ribs; cartilages of the nose, trachea, and larynx. Photomicrograph: Hyaline cartilage from the trachea (300x). Costal cartilages Chondrocyte in lacuna Matrix (f) Cartilage: hyaline
39. Figure 4.9g: Connective tissues (continued), p. 136. (g) Cartilage: elastic Description: Similar to hyaline cartilage, but more elastic fibers in matrix. Function: Maintains the shape of a structure while allowing great flexibility. Location: Supports the external ear (pinna); epiglottis. Photomicrograph: Elastic cartilage from the human ear pinna; forms the flexible skeleton of the ear (640x). Chondrocyte in lacuna Matrix
40. Figure 4.9h: Connective tissues (continued), pp. 137-138. Description: Matrix similar to but less firm than that in hyaline cartilage; thick collagen fibers predominate. Function: Tensile strength with the ability to absorb compressive shock. Location: Intervertebral discs; pubic symphysis; discs of knee joint. Photomicrograph: Fibrocartilage of an intervertebral disc (200x). Special staining produced the blue color seen. Intervertebral discs Chondrocytes in lacunae Collagen fiber (h) Cartilage: fibrocartilage
41.
42. Figure 4.9i: Connective tissues (continued), pp. 137-138. (i) Others: bone (osseous tissue) Description: Hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae. Very well vascularized Function: Bone supports and protects (by enclosing); provides levers for the muscles to act on; stores calcium and other minerals and fat; marrow inside bones is the site for blood cell formation (hematopoiesis). Location: Bones Photomicrograph: Cross-sectional view of bone (70x). Lacunae Lamella Central canal
43. Figure 4.9j: Connective tissues (continued), p. 138. Description: Red and white blood cells in a fluid matrix (plasma). Function: Transport of respiratory gases, nutrients, wastes, and other substances. Location: Contained within blood vessels. Photomicrograph: Smear of human blood (1500 ); two white blood cells (neutrophil in upper left and lymphocyte in lower right) are seen surrounded by red blood cells. Neutrophil Red blood cells Lymphocyte Plasma (j) Others: blood
44. Figure 4.10: Nervous tissue, p. 139. Photomicrograph: Neurons (100 ) Function: Transmit electrical signals from sensory receptors and to effectors (muscles and glands) which control their activity. Location: Brain, spinal cord, and nerves. Description: Neurons are branching cells; cell processes that may be quite long extend from the nucleus-containing cell body; also contributing to nervous tissue are nonirritable supporting cells (not illustrated). Cell processes Cell body Nuclei of supporting cells Cell body of a neuron Neuron processes Nervous tissue
45. Figure 4.11a: Muscle tissues, p. 140. Description: Long, cylindrical, m ultinucleate cells ; obvious striations. Function: Voluntary movement; locomotion; manipulation of the environment; facial expression; voluntary control. Location: In skeletal muscles attached to bones or occasionally to skin. Photomicrograph: Skeletal muscle (approx. 300x). Notice the obvious banding pattern and the fact that these large cells are multinucleate. Nuclei Part of muscle fiber (a) Skeletal muscle
46. Figure 4.11b: Muscle tissues (continued), p. 140. (b) Cardiac mus cl e Description: Branching, striated, generally uninucleate cells that interdigitate at specialized junctions (intercalated discs). Function: As it contracts, it propels blood into the circulation; involuntary control. Location: The walls of the heart. Photomicrograph: Cardiac muscle (800x); notice the striations, branching of cells, and the intercalated discs. Intercalated discs Nucleus
47. Figure 4.11c: Muscle tissues (continued), p. 141. Description: Spindle-shaped cells with central nuclei; no striations ; cells arranged closely to form sheets. Function: Propels substances or objects (foodstuffs, urine, a baby) along internal passageways; involuntary control . Location: Mostly in the walls of hollow organs. Photomicrograph: Sheet of smooth muscle (approx. 600 ). Smooth muscle cell Nuclei (c) Smooth muscle
48.
49. Figure 4.12a-b: Classes of membranes, p. 142. Cutaneous membrane (skin) Mucosa of nasal cavity Mucosa of lung bronchi Mucosa of mouth Esophagus lining (a) Cutaneous membrane (b) Mucous membranes
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